The present invention relates generally to a rotary roll extruder for extruding material, such as raw rubber from a notch of a mouthpiece in cooperation with an outer circumferential surface of a cylindrical extrusion roll to form extrusions in desired shapes. More particularly, it pertains to a mouthpiece discriminating device for such a rotary roll extruder.
One example of a hitherto used rotary roll extruder is shown in FIG. 1. This extruder includes a cylindrical rotary roll 1, a mouthpiece 2 arranged in opposition to the roll 1, and a die head 3 through which raw rubber is discharged from the extruder. The raw rubber is extruded through a notch of the mouthpiece 2 in cooperation with the outer circumferential surface of the rotary roll 1 to form extrusions 4. In the illustrated example, a restraining plate 5 serves to restrain the mouthpiece 2 in position.
With such an extruder, however, since the mouthpiece 2 is held by the restraining plate 5 as described above, it must be removed each time mouthpieces are exchanged. In order to avoid such troublesome operation, it may be feasible to use mouthpieces which are movable toward and away from the rotary roll in a radial direction thereof and which can be held at a predetermined position relative to the rotary roll 1.
In an extruder which includes exchangeable mouthpieces cooperating with the outer circumferential surface of the extruder roll, although there are some mouthpieces with characteristic appearance which can be easily distinguished from others by visual inspection, it is generally difficult for workers to quickly and correctly distinguish different kinds of mouthpieces from one another because of their inconspicuous differences in appearance. Moreover, discrimination of different kinds of mouthpieces relying upon visual inspection is not only troublesome, but also prone to error in selecting correct mouthpieces.